When a new facility nears mechanical completion, the hard part begins: proving every device, loop, and safeguard works the way the drawings say it should. 

Commissioning is where a pile of equipment becomes a plant. Three activities do most of the heavy lifting:

• End-to-end loop checks for controls and instrumentation.
• Pressure safety valve (PSV) testing.
• Vendor equipment validation.

Miss here, and the consequences escalate fast. A single misranged transmitter can drive a control loop into instability. A PSV that wasn’t verified at the right set point may not lift when you need it. Sloppy vendor handoff leaves you with packaged equipment that won’t meet spec. 

Systematic commissioning, driven by disciplined checklists and clear acceptance criteria, catches these issues before hydrocarbons hit the system and before schedules and safety take a hit.

Startup turns things on. Commissioning proves they’re right. Good checklists work in layers:

1. Installation: Is the device mounted, oriented, wired, and protected as designed? 
2. Function: Does it measure/actuate across the full range with the expected accuracy and response? 
3. Integration: Do connected systems (DCS/PLC, alarms, interlocks, ESD) behave correctly together?

Finding a wiring inversion during commissioning costs hours; finding it after startup can cost a shutdown. Digital commissioning tools now replace clipboards, giving real-time tracking, overdue flags, photos, and a clean audit trail when regulators or insurers ask for proof months later.

Set Up the Ground Truth

Come in with current P&IDs, loop sheets, cause-and-effect, and control narratives. Resolve any redlines before you test.

Field verification starts with basics: 

• Is the temperature element actually in a thermowell?
• The flowmeter installed with required straight-run?
• Junction boxes sealed? Glands tight?
• Impulse lines sloped and heat-traced where required?

On the system side, confirm that database points (tag, range, units, scaling, alarming) match the field device. If the pressure transmitter is ranged 0–100 psig, your DCS must be too. Units and setpoints included.

Test the Whole Loop, Not Just a Point

Drive the signal through the full range and watch the control system value. Check repeatability, hysteresis, and output response on valves (including travel limits and fail action). 

Use calibrated equipment with current, traceable certifications; “as-found” and “as-left” data belong on the sheet.

Metrological traceability means an unbroken chain of calibrations back to national or international standards (e.g., SI via NIST).

Fix the Usual Suspects

• Noise & VFD coupling: Keep instrument cabling separated/shielded; re-terminate shields correctly. 
• Ground loops: One ground reference per loop; isolate as required. 
• Database errors: Mismatched units (PSIA vs PSIG), swapped ranges, or wrong scaling often masquerade as “bad transmitters.”

Where loops are part of a safety instrumented function, ensure commissioning and validation align with IEC 61511 requirements across installation, commissioning, and validation steps.

Phase Your Way to Success

Break the project into bite-sized systems. Perhaps raw-materials handling this quarter, the primary process next, then utilities and offsites. Each slice gets planned outages, interface testing, and lessons learned you can roll into the next phase.

Mapping dependencies is everything: what you can isolate, what must move together, and where temporary bridges are required.

Run Old and New in Parallel

Standing up the new system beside the old lowers risk. Put the replacement into shadow mode by reading live inputs, executing control, but with outputs inhibited. Then you compare decisions.

Fix discrepancies while production stays on the legacy box. When it’s time to cut over, treat it like a flight checklist: roles, steps, fallback. Drill it until the team can do it under pressure.

Hot Cutover Tactics

If your maintenance window is measured in hours, preparation is your safety net. Pre-build and factory-test panels. Pre-pull and megger cables. Stage spare hardware. Rehearse the switchover on a sandbox rack so the techs’ muscle memory is dialed in.

And keep a rollback plan with pre-tested reversion images close at hand.

Follow the Rulebooks

PSVs are last-line protection. Their testing and acceptance are governed by API 520 (selection/sizing/installation) and API 527 (seat tightness), in coordination with ASME BPVC code requirements and National Board practices.

• Set pressure: Verify pop within allowed tolerance at the certified set point and with the correct backpressure setup per API guidance. 
• Seat tightness: Use the prescribed media and bubble-tightness methods for the service per API 527. 
• Inlet losses & chatter: Observe the 3% inlet pressure loss guidance in API 520 (and documented exceptions where a supplementary engineering analysis justifies otherwise).

Get the Paper Trail Right

Maintain complete certificates showing valve ID, set pressure, reseat, media, conditions, and calibration traceability.

Many jurisdictions and insurers expect rapid retrieval of PSV records; electronic document management makes audits painless.

Training and certification tied to ASME Section VIII and National Board programs help ensure correct methods and documentation.

Verify Interactions with Safeguards

PSVs don’t live alone. Confirm sequences with alarms, permissives, and shutdowns (high-pressure trip acts first; PSV is back-up).

Where plant logic trips a unit when a PSV lifts (via position switch), test the interlock for reliability without nuisance trips.

Line Up Support and Criteria Early

Pre-qualify for commissioning readiness: field service availability, documentation completeness, and a record of similar startups. Insist on full OEM packages (O&M, PM, spares, warranty terms).

Replace “pump shall run” with measurable acceptance criteria: flow, head, efficiency window, vibration, bearing temps, NPSH margin, and power draw.

Keep Communication Clean

Use a shared workspace for drawings, procedures, and punch items. Meet routinely during critical phases; track actions to closure. Define escalation early so disputes (e.g., “meets spec vs. doesn’t”) don’t stall the schedule.

Witness, Punch, Prove

Witness the critical tests, record objective data, and keep punch lists specific and owned. Follow up with performance tests under real site conditions; packaged systems that sail through shop tests sometimes struggle with actual process fluid or utilities.

Make Every Line Item Observable and Measurable

“Verify installation” is vague.

“Confirm PT-101 installed per 123-P-001 with orientation/impulse line slope; weather-tight JB; gland torque per spec” tells the tech what good looks like.

Standardize templates, then tailor for context: offshore (salt/motion), arctic (cold/icing), refining (multi-product), etc.

Go Digital Where It Helps

Tablet-based checklists with photos and timestamps cut admin load and boost traceability. Integrate with your CMMS so commissioning data seeds PM strategies from day one.

For procedural steps, like startup, shutdown, and abnormal response, adopt ISA-106/procedural automation concepts to capture and execute best-known sequences consistently.

Roles, Training, and Safety

Be explicit about who owns what (commissioning manager, system leads, field supervisors, OEM reps). Train technicians on both general methods and equipment specifics; verify competency before critical work.

For SIS-related commissioning/validation, align with IEC 61511 lifecycle expectations (verification vs. validation, cause-and-effect, proof testing foundations).

Metrics and Learning

Track schedule adherence, first-time-quality, safety stats, and cost. Run post-project reviews and capture lessons into your templates so the next project starts smarter.

Disciplined loop checks produce trustworthy signals and predictable control. 

PSV verification proves your last safeguard.

Tight vendor coordination ensures packages do what the datasheet promises.

Invest in standards-based methods and digital traceability now, and you’ll start up cleaner, audit easier, and operate safer.